This invention relates to a security system that is tamper resistant and can be detected with automated means such as scanners, readers and detectors. More specifically, it relates to ultraviolet (UV) fluorescent chemistry for additional security protection. In the preferred embodiment, frequency specific, insoluble UV chemicals may be used as well to further improve security.
In recent years, counterfeits and forgery have become increasingly severe problems for major name brand manufacturers, governments, banking and financial industry. The rapid growth in popularity for flea markets, bartering, underground discount vendors, and gray markets, fueled by worldwide recessions and illicit traffic create strong demands for technologies and systems that can deter and detect counterfeit. Additionally, security protection devices are preferably machine readable to reduce dependency on subjective human judgment while providing cost saving in labor through automated processing.
Presently, the state of art security protection devices typically use visible means. Three-dimensional holographic labels, micro-dot printing, or "rotogravure dot patterns," self-destructive labels, tamper resistant tags and bar codes, and other machine readable codes, etc., are all visible. With the exception of bar codes, verification typically relies on human subjective judgment making counterfeit or copying relatively easy and authentication prone to errors. They also require additional space in the product or packaging for placement and, therefore, could interfere with the artistic layout of the product or packaging. Many of them can be removed, replaced and re-applied without discrimination, therefore reducing their effectiveness as high security counterfeit protection devices. More importantly, the advanced color copier and computer graphic technologies can reproduce practically any visible printing making counterfeit proof security systems and detection almost impossible.
Electronic means, such as magnetic strips, surface acoustic wave devices, micro chips, smart cards, etc., offer excellent encryption capability and can be fully automated for authentication and processing. The problems are that they tend to be more bulky in size, more susceptible to environmental interference, more expensive, and less robust.
Infrared-based systems, on the other hand, overcome many of the shortcomings described earlier. They are invisible and have encryption capability. They are also relatively low cost and non-removable. While authentication can be easily automated, their total invisibility makes consumer education rather difficult and do not provide a quick and inexpensive way for first order identification in the field.
Visible erase-detectable paper and security labels have been around for some time. Most notable is "water-mark" paper where patterns become smeared if it is exposed to fluid or erased. Recently, advanced synthetic paper fabric such as Teslin (silica-filled polyolenfinic media) which wrinkles upon erasing mechanically. However, most such devices, for example, laser printed patterns, "water marks, " and including Teslin can be erased without blemish with chemicals as simple as alcohol. The patterns can then be reconstructed or touched up again with matching "visible" ink.
As far as security labels are concerned, there are several manufacturers who produce labels that will be deformed, damaged, destroyed, upon removal or tampering. Similarly, UV-sensitive materials have been used as invisible marking of various types. See, for example, Green, Miller U.S. Pat. No. 4,889,367; Duret U.S. Pat. No. 4,605,846.
UV-based technologies, on the other hand, overcome most of the shortcoming described above. They are machine-readable, can be partially visible or invisible, and current advanced copying machine and computer graphic technologies cannot be used to copy UV sensitive materials because UV spectrum is beyond the visible range of almost all vision-based technologies. It is, therefore, highly desirable to apply UV-based technologies for security protection for many products. However, typical patterns printed with UV inks today are not erasable.